We talked about this in a previous thread but I’m now pretty sure this is a good idea and it seems easy to implement. You know the “Show Live” button?
I think it should be split into a button and checkbox.
The button part would be the same as now but I think it should be labeled “Launch/Refresh App” rather than “Show Live”. 
And the checkbox would be the “Refresh App on Changes” checkbox currently tucked away in the user menu. It could be called “Auto-Refresh” or “Auto-Refresh As You Type”. The juxtaposition with the button would make it pretty quickly self-explanatory.
Why it’s important
Whenever my app gets bogged down, typically due to my own bug or boneheadedness (or sometimes legit computational intensiveness), it brings the IDE to its knees and it’s super frustrating. Having a quick way to toggle Auto-Refresh and always be aware when it’s toggled on would be pretty great.
You’d think it wouldn’t be a big deal to toggle it from the menu but I tend to wait till I’m pretty frustrated with lagginess before I do. Not so much because of the two extra clicks (open menu, toggle, close menu) but because when my app is snappy again I really want Auto-Refresh back on but I forget that it’s off and have a new round of frustration that it’s not refreshing as I type. Or just the uncertainty about if I should expect my changes to be magically reflected – it keeps making debugging harder than it should be.
In conclusion: I really want a visible indicator that Auto-Refresh is happening and a one-click toggle of it.
PS: What if you solved editor lagginess completely, so the editor is never hung up no matter what the app is doing? I argue that even then this is worth doing. Having the app reload itself over and over as you type is sometimes going to be unwanted behavior no matter what. So a quick way to toggle it and know when it’s supposed to be happening is valuable.
 And maybe it’s also easy for the button label to dynamically change between “Launch App” and “Refresh App” depending on whether there’s already a tab connected showing the app. It’s common to lose track of whether there’s already a connected tab, or maybe it crashed and lost its connection to the IDE. Anyway, this footnote is the least important part of my proposal!